What are Cloudflare's caching levels?

You can set the Cloudflare CDN to cache static content according to these levels:

No Query String / Basic: Only delivers resources from cache when there is no query string.

Ignore Query String / Simple: Delivers the same resource to everyone independent of the query string (Note: The Ignore Query String setting only applies to static file extensions. This setting will remove the query string when generating the cache key, so that a request for "style.css?something" will be normalised to just "style.css" when serving from the cache.).

Standard / Aggressive: Delivers a different resource each time the query string changes.